Prior art hydraulic lift arrangements for tilting the cab of a truck are illustrated in the London U.S. Pat. No. 3,472,547, issued Oct. 14, 1969; the Spear U.S. Pat. No. 2,306,348, issued Dec. 22, 1942; the Reynolds et al U.S. Pat. No. 3,801,151, issued April 2, 1974, and the Reynolds et al U.S. Pat. No. 3,875,850.
As illustrated in those patents, truck cabs are commonly hinged to a forward portion of the truck chassis and the cabs are supported for tilting movement upwardly and forwardly to permit work on the truck engine. The cab is commonly supported by a double acting hydraulic cylinder such that extension of the cylinder causes forward tilting movement of the cab. Hydraulic pumps and valve assemblies are provided for selectively supplying hydraulic fluid to the double acting hydraulic cylinder and movement of the cab between the operating position and the forward tilting position.